Airfoils for gas turbine blades are typically manufactured by precision casting or forging. Casting is usually preferred when internal cooling features are required. When solid blades without internal cooling passages are acceptable, forging may be used. However, neither of these conventional manufacturing processes may be suitable for very large turbine blades that require internal cooling. In addition to the challenges associated with the casting of very large blades, such as the control of wall thickness, avoidance of core breakage, and dimensional control, the resulting blade may be too heavy and may exceed the allowable blade disc loading because the minimum practical wall thickness that can be cast reliably becomes a limiting factor in the blade design.
Super-plastic forming is used commercially in the manufacture of large titanium alloy fan blades for aero engines. However, nickel-based superalloys will be required for some land-based turbine designs due to higher operating temperatures. Such alloys are not suitable for super-plastic forming.